The 2023 Six Nations Under 20s Championship was the 16th Six Nations Under 20s Championship, the annual northern hemisphere rugby union championship for players under 20 years of age.

Ireland retained the championship, their fifth, winning all five matches as they had done in the last tournament to record a fourth Grand Slam.

[1][2] Ireland became the first team to win back-to-back Grand Slams in the history of the tournament.

Table ranking rules [8]